Xen users - Dec 2013 - domU fails to reboot if disks use drbd resources

Hi!

dom0: Ubuntu 10.4 64bit, Xen 4.0.1, Kernel 2.6.32.24-xen, DRBD 8.3.7
domU: Ubuntu 10.4 64bit, Kernel 2.6.32-33-server

I never had any issues when executing "reboot" in the domU - the domU 
was just rebooted.

Recently I changed the domU config to use the DRBD disk handler:

disk        = [
-                  ''phy:/dev/drbd6,xvda2,w'',
+                  ''drbd:cc-stat-ha,xvda2,w'',
               ]

Startup of the domU works as expected, but when I execute "reboot" in 
the domU the domU either is shutdown, or hangs with "Will restart now"
as last line in the console.

I suspect a problem when detaching/reattaching to the DRBD device, but I 
didn''t found any errors in syslog.

Any hints are appreciated.

Thanks
Klaus